Colloids versus crystalloids for fluid resuscitation in critically ill patients

Colloid solutions are widely used in fluid resuscitation of critically ill patients. There are several choices of colloid and there is ongoing debate about the relative effectiveness of colloids compared to crystalloid fluids.

To assess the effects of colloids compared to crystalloids for fluid resuscitation in critically ill patients.

We searched the Cochrane Injuries Group's specialised register, CENTRAL, MEDLINE, EMBASE, the National Research Register, Web of Science and MetaRegister. Bibliographies of trials and review articles retrieved were searched. The searches were last updated in December 2006.

Randomised controlled trials (RCTs) of colloids compared to crystalloids, in patients requiring volume replacement. Cross-over trials and trials in pregnant women and neonates were excluded.

Two authors independently extracted data and rated quality of allocation concealment. Trials with a 'double-intervention', such as those comparing colloid in hypertonic crystalloid to isotonic crystalloid, were analysed separately. The analysis was stratified according to colloid type and quality of allocation concealment.

We identified 63 eligible trials, 55 of these presented mortality data. COLLOIDS COMPARED TO CRYSTALLOIDS: Albumin or plasma protein fraction - 23 trials reported data on mortality, including a total of 7,754 patients. The pooled relative risk (RR) from these trials was 1.01 (95% confidence interval [95% CI] 0.92 to 1.10). When the trial with poor quality allocation concealment was excluded, pooled RR was 1.00 (95% CI 0.91 to 1.09). Hydroxyethyl starch - 16 trials compared hydroxyethyl starch with crystalloids, n = 637 patients. The pooled RR was 1.05 (95% CI 0.63 to 1.75). Modified gelatin - 11 trials compared modified gelatin with crystalloid, n = 506 patients. The pooled RR was 0.91 (95% CI 0.49 to 1.72). Dextran - nine trials compared dextran with a crystalloid, n = 834 patients. The pooled RR was 1.24 (95% CI 0.94 to 1.65). COLLOIDS IN HYPERTONIC CRYSTALLOID COMPARED TO ISOTONIC CRYSTALLOID: Eight trials compared dextran in hypertonic crystalloid with isotonic crystalloid, including 1,283 randomised participants. Pooled RR was 0.88 (95% CI 0.74 to 1.05).

There is no evidence from RCTs that resuscitation with colloids reduces the risk of death, compared to resuscitation with crystalloids, in patients with trauma, burns or following surgery. As colloids are not associated with an improvement in survival, and as they are more expensive than crystalloids, it is hard to see how their continued use in these patients can be justified outside the context of RCTs.